What's the difference between a basic inductive timing light and a digital advance timing light?

A basic inductive timing light flashes in sync with the number-one spark plug so you can read static timing marks on the harmonic balancer. A digital advance model adds a built-in advance dial or readout, letting you check total and mechanical advance without paint-marking extra degrees on the pulley, and many also display RPM, dwell, or voltage. Buyers working on carbureted or distributor-equipped engines tend to favor the advance-capable units.